The present invention relates generally to apparatus for adjusting the height of a table, chair or like article. In particular the present invention relates to height adjusting apparatus of the type which includes a base to which at least one substantially vertical guide is connected and a table or the like connected to a slide which is movable within the guide and wherein a locking mechanism is provided for locking the table or the like at a desired height.
It is desirable in many instances to provide a table or the like with the capability of having its height adjusted to suite particular circumstances. For example, in cases where a table supports a keyboard, such as for use in connection with a computer terminal, an adjustability of the height of the table to suite the particular requirements of an operator is advantageous.
The most expeditious arrangement for providing a table or the like with a height adjusting capability is to connect one or more slides to the table and to situate the slides within corresponding substantially vertical guide tubes so that the slides can be telescoped within the guide tubes. In the past, the slides have been locked at their desired position within the guide tubes by one of two basic ways. In one arrangement, a plurality of bores may be formed in one of the guide tubes or slides and one or more bores formed in the other so that the bores in the respective elements are alignable with each other whereupon a pin or the like can be inserted into aligned bores to lock the slide within the guide member. However, this arrangement is disadvantageous in that removal of the pin for subsequent readjustment of the height is inconvenient and, moreover, only a stepwise or discreet rather than continuous adjustment can be achieved. In another arrangement, a clamp or set-screw is provided in the guide which can be tightened when the slide is at its desired position. However, this arrangement is disadvantageous in that since the thread of the set-screw or clamp will be subjected to large stresses when it is tightened, an inherent weakness in the structure exists.
It is the primary object of the present invention to provide new and improved apparatus for adjusting the height of a table, chair or the like which overcomes the problems of the prior art described above.
Another object of the present invention is to provide new and improved apparatus for adjusting the height of a table, chair or the like which is simple to use, quick and reliable in operation, and wherein the slide is free of any wobble or play within the corresponding guide tube to provide a rigid construction.
Briefly, in accordance with the present invention these and other objects are attained by providing in the slide-guide tube arrangement described above, a locking mechanism including at least one wedge member mounted on the slide and at least one locking member positioned in the space defined between the wedge member and the guide tube. The locking member, which preferably takes the form of a rod, is normally urged into a wedged position in mutual engagement with the wedge surface of the wedge member and the guide tube to prevent movement of the slide within the guide tube. A releasing mechanism is also provided for moving the locking member in a substantially vertical direction out of its wedge position to permit the position of the slide to be adjusted within the guide tube.
The use of a wedge member as the locking mechanism in apparatus for adjusting the height of a table, chair or the like is advantageous in that it allows a continuous or infinite adjustment of the height of the slide while providing an efficient and rigid locking of the slide to the guide tube. In connection with the latter advantage, the use of a wedge and associated locking member results in a stronger locking force being created the larger the load to which the table, chair or the like is subjected.
According to a preferred embodiment of the invention, the locking member is urged into wedging engagement in the space defined between the wedge member and the guide tube by means of spring means. The releasing mechanism includes a releasing arm extending along the guide tube which is coupled to the locking member and which can be actuated to move the latter out of its wedging position to release the slide for movement within the guide tube. In accordance with another feature of the invention, the releasing arm advantageously extends to the region of the table or the like and a lever is provided through the pivoting of which the releasing arm is moved in the direction of the guide tube. The lever may be situated in proximity to the front edge of the table or chair in which case the adjustment of the height can be accomplished in a quick and easy manner.
If the table or the like is relatively light and it is desired to secure the same so as to also prevent upward movement thereof, in accordance with another feature of the present invention, at least one wedge member and corresponding locking member is provided for preventing the downward motion of the slide within the guide tube and at least one wedge member and corresponding locking member is provided for also preventing the upward movement of the slide within the guide tube. Where this feature is provided, the releasing mechanism may be constituted by a pair of releasing arms, one of which functions to move the first locking member in a downward direction to allow downward movement of the slide within the guide tube whereas the second releasing arm functions to move the second locking member upwardly for allowing the slide to be raised within the guide tube. At least one spring means are provided for urging the locking members into the respective wedged positions. The apparatus may be designed so that a lever situated in the vicinity of the table or the like will function to move the first releasing arm downwardly and at the same time move the second releasing arm upwardly to allow the slide to be either lowered or raised within the guide tube.
The apparatus is preferably constructed in a symmetrical manner wherein the locking apparatus comprises a pair of first wedge members and a corresponding pair of first locking members which function to prevent downward movememt of the slide means and a pair of second wedge members and a corresponding pair of second locking members which function to prevent the upward movement of the slide within the guide tube.